# ESPresso Frame Firmware

ESP-IDF firmware for the ESP32-C6. On first boot it provisions itself over
a WiFi captive portal; after that it wakes on a timer, fetches an
already-processed frame from the [server](../server/), streams it straight
to the panel over SPI, and goes back to deep sleep.

See [`docs/architecture.md`](../docs/architecture.md) for the full boot/fetch
cycle and [`docs/hardware.md`](../docs/hardware.md) for wiring.

## Build and flash

Requires [ESP-IDF](https://docs.espressif.com/projects/esp-idf/en/stable/esp32c6/get-started/)
(developed against v5.x/v6.x) with the environment sourced (`. $IDF_PATH/export.sh`
or your distro's equivalent).

```
idf.py set-target esp32c6
idf.py build
idf.py -p PORT flash monitor
```

(`Ctrl-]` exits the monitor.)

The committed [`sdkconfig.defaults`](sdkconfig.defaults) pins an 8MB flash
size and a custom [`partitions.csv`](partitions.csv) (2MB app partition --
the default "single app" ~1MB partition runs out of room once the HTTP
client, TLS, and vendored fonts/QR library are linked in). If your board
has less flash, you'll need to shrink the app partition and drop features
to fit.

## Configuration (`idf.py menuconfig`)

Under **ESPresso Frame Configuration**:

| Option | Default | What it does |
| --- | --- | --- |
| `ESP_AP_SSID` | `ESPRESSO` | Provisioning softAP SSID prefix (device appends `_XXXXXX` from its MAC) |
| `ESP_MAX_STA_CONN` | 4 | Max clients on the provisioning softAP |
| `ESP_ENABLE_DHCP_CAPTIVEPORTAL` | on | DHCP Option 114 captive portal detection |
| `FRAME_STA_CONNECT_MAX_RETRIES` | 3 | Home WiFi connect attempts before falling back to provisioning |
| `FRAME_STA_CONNECT_TIMEOUT_MS` | 15000 | Per-attempt WiFi connect timeout |
| `FRAME_SERVER_CHECK_TIMEOUT_MS` | 3000 | Timeout for `GET /frame/config` (reachability check + refresh interval) |
| `FRAME_FETCH_TIMEOUT_MS` | 15000 | Timeout for `GET /frame/image` |
| `FRAME_SLEEP_INTERVAL_S` | 3600 | **Fallback only** -- the refresh interval is normally set server-side; see below |
| `FRAME_RETRY_INTERVAL_S` | 300 | Sleep duration after a failed cycle, before retrying |
| `FRAME_RESET_BUTTON_GPIO` | 3 | Factory-reset button GPIO (-1 to disable). Must be 0-7 (ESP32-C6's deep-sleep-wakeup-capable pins) |
| `FRAME_RESET_BUTTON_HOLD_MS` | 10000 | How long the button must be held to trigger a reset |
| `FRAME_NEXT_BUTTON_GPIO` | 2 | Next-photo button GPIO (-1 to disable). Must be 0-7 |
| `FRAME_MANAGE_BUTTON_GPIO` | 1 | "Scan to manage" button GPIO (-1 to disable). Must be 0-7 |

Under **E-Paper Display (epd7in3e) Configuration**: SPI/GPIO pin
assignments and SPI clock speed -- see
[`docs/hardware.md`](../docs/hardware.md) for the wiring these correspond to.

### Why `FRAME_SLEEP_INTERVAL_S` says "fallback"

The actual refresh interval is set from the server's web UI (see
[`server/README.md`](../server/README.md)) and delivered to the device on
every wake via `GET /frame/config`, so it can be changed without
reflashing. The Kconfig value only applies before the device has ever
successfully reached a configured server, or if the response doesn't
include a valid interval.

## First boot

With no stored WiFi config (a fresh device, or after erasing NVS -- see
below), the device brings up the display before anything else and shows a
two-step setup screen:

1. **Connect to WiFi** -- a QR code encoding `WIFI:T:WPA;S:...;P:...;;`
   for the device's own `ESPRESSO_XXXXXX` softAP, with the SSID and
   password also printed underneath for anyone provisioning from a
   desktop/laptop that can't scan a QR code.
2. **Configure device** -- a QR code linking straight to the captive
   portal's config page (`http://192.168.4.1/` by default), for a
   one-scan shortcut once you've joined the AP.

The config page asks for your home WiFi SSID/password and the "Tools
Server" address (`host:port` of the [server](../server/) -- **not** your
Immich server). Saving reboots the device, which then connects to your
home network and starts its normal fetch/sleep cycle.

## Skipping to the next photo

Wire a momentary push button between GPIO2 and GND (internal pull-up,
active-low, same wiring style as the reset button). A press wakes the
device (if asleep) and tells the server to advance to the next photo
right away, regardless of the configured refresh interval -- no long hold
needed, unlike the factory-reset button, since advancing is easily
reversible by pressing again. See `FRAME_NEXT_BUTTON_GPIO` above to
change the pin or disable the feature.

Normal wakes and reboots never advance the photo on their own -- the
server decides when to advance based on its own clock (see
[`server/README.md`](../server/README.md)), so an unplanned reboot just
redisplays whatever was already showing instead of skipping ahead.

## Scanning to manage the queue

Wire a momentary push button between GPIO1 and GND (same wiring style as
the other two buttons). A press wakes the device and overlays several
corners of whatever photo is currently showing, leaving the middle of
the photo visible and unchanged:

- **Top-right**: a QR code -- "SCAN TO MANAGE" -- linking to the
  server's config page.
- **Top-left**: the photo's location, if Immich reverse-geocoded it from
  GPS EXIF (skipped entirely if not).
- **Bottom-right**: the date the photo was taken, if known.
- **Bottom-left**: a QR code linking to a public, view-only Immich share
  link for that exact photo. The link is only created once someone
  actually scans it, and expires 30 minutes after that.

After 30 seconds with no further presses it automatically reverts to the
plain photo. Pressing the button *again* while this is up escalates to a
second menu level -- everything above, plus the name of anyone Immich
has identified labeled right next to their face in the photo (skipped
for faces Immich hasn't been told a name for; no face detection happens
on the device or the server, this is entirely Immich's own People
feature). A third press exits immediately rather than waiting out the
30-second timer. See `FRAME_MANAGE_BUTTON_GPIO` above to change the pin
or disable the feature.

The device stays awake the whole time (up to three physical refreshes:
the base overlay, the escalated one, and reverting), so this costs
meaningfully more power than a normal wake -- expected for a deliberate,
occasional action, same tradeoff as the other two buttons.

## Resetting to provisioning mode

Wire a momentary push button between GPIO3 and GND (internal pull-up,
active-low -- no external resistor needed). Hold it for 10 seconds (from
either power-on or while the device is deep-asleep -- GPIO3 is armed as a
wakeup source) and it clears the stored WiFi/server config and restarts
into provisioning. Releasing it early is a no-op; nothing happens until
the full hold duration elapses, so a brief accidental bump won't
reprovision the device. See `FRAME_RESET_BUTTON_GPIO`/
`FRAME_RESET_BUTTON_HOLD_MS` above to change the pin or hold duration, or
disable the feature.

Without the button wired up (or with `FRAME_RESET_BUTTON_GPIO` set to
`-1`), reconfiguring still works by erasing the NVS partition over USB:

```
python -m esptool --chip esp32c6 -p PORT erase-region 0x9000 0x6000
```

(Offset/size match the `nvs` entry in [`partitions.csv`](partitions.csv);
this only wipes the config, not the app itself.)